[WFCORE-6962] Add another check that candidates exist

[bstansberry]

Also clean up a bunch of IDE complaints about using 'isEmpty()'

https://issues.redhat.com/browse/WFCORE-6962

[wildfly-ci]

Core -> Full Integration Build 13979 outcome was FAILURE using a merge of 1271dac
Summary: Tests failed: 1 (1 new), passed: 3991, ignored: 60 Build time: 02:04:56

Failed tests

org.jboss.as.test.clustering.cluster.ejb.timer.DistributedTimerServiceTestCase.test: java.lang.AssertionError: class org.jboss.as.test.clustering.cluster.ejb.timer.beans.AutoPersistentTimerBean={node-1=[]}. Actual: 0
	at org.jboss.as.test.clustering.cluster.ejb.timer.AbstractTimerServiceTestCase.test(AbstractTimerServiceTestCase.java:305)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at jdk.internal.reflect.GeneratedMethodAccessor27.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at jdk.internal.reflect.GeneratedMethodAccessor26.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at jdk.internal.reflect.GeneratedMethodAccessor25.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at jdk.internal.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at jdk.internal.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at jdk.internal.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at jdk.internal.reflect.GeneratedMethodAccessor15.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at jdk.internal.reflect.GeneratedMethodAccessor14.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at jdk.internal.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at jdk.internal.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at jdk.internal.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
------- Stdout: -------
node-2 2024-10-14 16:25:13,401 INFO  [org.jboss.modules] (main) JBoss Modules version 2.1.5.Final
node-2 2024-10-14 16:25:13,839 INFO  [org.jboss.msc] (main) JBoss MSC version 1.5.5.Final
node-2 2024-10-14 16:25:13,847 INFO  [org.jboss.threads] (main) JBoss Threads version 2.4.0.Final
node-2 2024-10-14 16:25:13,942 INFO  [org.jboss.as] (MSC service thread 1-2) WFLYSRV0049: WildFly 34.0.0.Final-SNAPSHOT (WildFly Core 27.0.0.Beta1-SNAPSHOT) starting
node-2 2024-10-14 16:25:15,086 INFO  [org.wildfly.security] (Controller Boot Thread) ELY00001: WildFly Elytron version 2.6.0.Final
node-2 2024-10-14 16:25:15,826 INFO  [org.jboss.as.server] (Controller Boot Thread) WFLYSRV0039: Creating http management service using socket-binding (management-http)
node-2 2024-10-14 16:25:15,848 INFO  [org.xnio] (MSC service thread 1-7) XNIO version 3.8.16.Final
node-2 2024-10-14 16:25:15,854 INFO  [org.xnio.nio] (MSC service thread 1-7) XNIO NIO Implementation Version 3.8.16.Final
node-2 2024-10-14 16:25:15,925 INFO  [org.jboss.as.naming] (ServerService Thread Pool -- 48) WFLYNAM0001: Activating Naming Subsystem
node-2 2024-10-14 16:25:15,958 INFO  [org.jboss.remoting] (MSC service thread 1-7) JBoss Remoting version 5.0.29.Final
node-2 2024-10-14 16:25:15,968 INFO  [org.jboss.as.clustering.infinispan] (ServerService Thread Pool -- 40) WFLYCLINF0001: Activating Infinispan subsystem.
node-2 2024-10-14 16:25:15,951 WARN  [org.jboss.as.txn] (ServerService Thread Pool -- 53) WFLYTX0013: The node-identifier attribute on the /subsystem=transactions is set to the default value. This is a danger for environments running multiple servers. Please make sure the attribute value is unique.
node-2 2024-10-14 16:25:15,961 INFO  [org.jboss.as.jaxrs] (ServerService Thread Pool -- 42) WFLYRS0016: RESTEasy version 6.2.10.Final
node-2 2024-10-14 16:25:15,983 INFO  [org.jboss.as.naming] (MSC service thread 1-2) WFLYNAM0003: Starting Naming Service
node-2 2024-10-14 16:25:15,990 INFO  [org.wildfly.extension.io] (ServerService Thread Pool -- 41) WFLYIO001: Worker 'default' has auto-configured to 8 IO threads with 64 max task threads based on your 4 available processors
node-2 2024-10-14 16:25:16,045 INFO  [org.jboss.as.connector] (MSC service thread 1-5) WFLYJCA0009: Starting Jakarta Connectors Subsystem (WildFly/IronJacamar 3.0.10.Final)
node-2 2024-10-14 16:25:16,062 INFO  [org.jboss.as.clustering.jgroups] (ServerService Thread Pool -- 44) WFLYCLJG0001: Activating JGroups subsystem. JGroups version 5.2.29
node-2 2024-10-14 16:25:16,079 INFO  [org.wildfly.extension.undertow] (MSC service thread 1-4) WFLYUT0003: Undertow 2.3.17.Final starting
node-2 2024-10-14 16:25:16,116 INFO  [org.jboss.as.connector.subsystems.datasources] (ServerService Thread Pool -- 32) WFLYJCA0004: Deploying JDBC-compliant driver class org.h2.Driver (version 2.2)
node-2 2024-10-14 16:25:16,160 INFO  [org.jboss.as.connector.deployers.jdbc] (MSC service thread 1-1) WFLYJCA0018: Started Driver service with driver-name = h2
node-2 2024-10-14 16:25:16,212 WARN  [org.wildfly.extension.elytron] (MSC service thread 1-4) WFLYELY00023: KeyStore file '/opt/buildAgent/work/e8e0dd9c7c4ba60/full/testsuite/integration/clustering/target/wildfly-clustering-ejb-2/standalone/configuration/application.keystore' does not exist. Used blank.
node-2 2024-10-14 16:25:16,213 INFO  [org.jboss.as.ejb3] (MSC service thread 1-5) WFLYEJB0481: Strict pool slsb-strict-max-pool is using a max instance size of 16 (per class), which is derived from thread worker pool sizing.
node-2 2024-10-14 16:25:16,217 INFO  [org.jboss.as.ejb3] (MSC service thread 1-6) WFLYEJB0482: Strict pool mdb-strict-max-pool is using a max instance size of 16 (per class), which is derived from the number of CPUs on this host.

[yersan]

Thanks @bstansberry